Circuit interrupters



June 21, 1960 E. J. WALKER ETAL 2,942,083

CIRCUIT INTERRUPTERS 3% Fig. I.

4 Sheets-Sheet 1 Filed Dec. 24, 1956 Fig. 3.

INVENTORS Eugene J. Walker 8 Howard E. Reichert.

BY W/RW WITNESSES ATTORNEY June 21, 1960 E. J. WALKER ETAL 2,942,083

CIRCUIT INTERRUPTERS Filed Dec. 24, 1956 4 Sheets-Sheet 2 63 6| F|g.6. -xxm June 21, 1960 E. J. WALKER ETAL 2,942,083

CIRCUIT INTERRUPTERS 4 Sheets-Sheet 3 Filed Dec. 24, 1956 June 21, 1960 E. J. WALKER ETAL 2,942,083

CIRCUIT INTERRUPTERS Filed D80. 24, 1956 4 Sheets-Sheet 4 8. UU 6 9 plow. HQ 4 7 9 w a m we 3% .l 7 6 g F V rll 1H w: .m 9 4 F 7 m 6 5 8 Fig.22.

Patented June 21, 1960 cmcurr INTERRUPTERS Eugene J. Walker, Borough Township, Beaver County, and Howard E. Reichert, Beaver, Pa., assrgnors to Westinghouse Electric Corporation, East Pittsburgh, Pa., a corporation 'of Pennsylvania Filed Dec. 24, 1956, Ser. No. 630,264

8 Claims. (Cl. 200-144) This invention relates to circuit interrupters in general and, more particularly, to arc exti-nguishing structures and contact operating mechanisms therefor.

A general object of the invention is to provide an unproved circuit interrupter in a very small, compact space. As well-known by those skilled in the art, and as dictated by the requirements of the industry, it hasbecome increasingly necessary to raise the power requlrements in the electrical industry, but at the same time space requirements have become more stringent, and the 1ndustry demands that the circuit interrupters require only a minimum amount of space.

In many applications, it is necessary to locate a circuit interrupter at a place where the space utilized by the circuit interrupter is a minimum. general object of the present invention to relocate, and to position the several component parts of a circuit interrupter such that the circuit interrupter is capable of interrupting a considerable amount of power, yet requiring no more space than would be used by a lowercapacity circuit interrupter. By one application of the present invention it is possible to provide a circuit interrupter capable of interrupting a 600 volt circuit, yet employing a housing customarily used for a 250 volt breaker.

Another object of the invention is to provide an improved arc-extinguisher for a circuit interrupter utilizing an improved configuration of the plate structure.

Still a further object of the present invention is to intersperse among the conducting plates of a spaced plate type of arc-extinguisher, insulating plates of generally U-shape.

Yet a further object of the present invention is to provide an improved arc-extinguisher of the spaced-plate type, in which pairs of insulating spaced strips are employed between adjoining conducting plates of the arcextinguisher.

A further object of the present invention is to form the conducting plates of a spaced-plate type of arc-extinguisher such that U-shaped insulating strips maybe readily assembled and maintained in position.

A further object of the present invention is to provide an improved and more effective housing structure for a spaced-plate type of arc-extinguisher, whereby improved venting may be obtained.

Still a further object of the invention is to so locate the stationary contact of a circuit interrupted such that a maximum distance is provided in the open-circuit position of the interrupter between said stationary contact and the movable contact.

Another object is to leave only a relatively thin insulating layer between the stationary contact of a circuit interrupter and the lower surface of the base therefor, so that a maximum separation distance exists between the stationary and movable contacts in the fully open-circuit position of the interrupter.

I Yet a further object of the invention is to provide an,

It is, therefore, a

improved, high-capacity circuit interrupter occupying a mini-mum space, and having the stationary contact therefor disposed at the end of a conducting strip, which turns rather sharply upwardly away from the bottom of the base for the circuit interrupter, leaving the relatively stationary contact separated from the lower surface of the base by only a relatively thin portion of insulating material. As a consequence of this construction, the stationary contact is positioned at the lowermost extremity of the circuit interrupter, with only a relatively thin insulating layer on the mounting side of the relatively stationary contact. Preferably, said relatively stationary contact is secured upon the end of a conducting strip, which turns sharply upwardly away from. the lower extremity of the base portion, and may be secured adjacent its other end to a terminal connection for the circuit interrupter.

Another object of the invention is to provide an improved housing for a spaced-plate type of arc-extinguisher, in which an insulating cover, or plate is utilized in conjunction with a U-shaped insulating wrapper having an upper extended portion, with a vent opening being provided adjacent an exterior opening of the cover for the,

interrupter. Preferably, conducting plates, having notches at their rear corners, are employed in conjunction with such an improved housing structure to facilitate the external venting of the arc gases.

Still a further object of the present invention is to provide an improved mounting of a contact arm relative to the switch arm, with a lost-motion connection therebetween, so that by employing suitable biasing means the contact arm may be biased to a very low extremity position immediately adjacent to the lower external surface of the base of the interrupter.

Another object is to so position the spaced plates of the arc-extinguisher and the arrangement of the contact operating mechanism in such a manner that a maximum separation distance exists between the spaced contacts in the fully open-circuit position of the interrupter, and, in addition, venting is facilitated through the arcextinguisher so that the possibility of restriking of the extinguished arc will be eliminated following the interr-uption process.

Further objects and advantages will readily become apparent, upon reading the following specification, taken in conjunction with the accompanying drawings, in which:

Figure 1 is a vertical sectional view through a threepole circuit interrupter embodying the principles of the present invention, with the contact structure being illustrated in the fully open-circuit position;

Fig. 2 is a fragmentary view similar to that of Fig. 1, but illustrating the position of the contact structure in the closed-circuit position thereof;

Fig. 3 is a fragmentary end elevational view of the circuit interrupter, as viewed from the right-hand end of Fig. 1, showing one of the screened, external vents in the cover of the interrupter;

Fig. 4 is a considerably enlarged vertical sectional view taken through the spaced-plate arc-extinguisher;

Fig. 5 is a sectional view taken along the line VV of Fig. 4, looking in the direction of the arrows;-

Figs. 610 are plan views of plate details, with Fig. 9 being a side elevational view of the plate of Fig. 10;

Figs. 1113 are side, plan and end elevational views of the insulating wrapper for the arc-extinguisher housing;

Fig. 14 is a considerably enlarged fragmentary side elevational View, partially in section, showing the contact structure in the closed-circuit position, with the lost- Fig. 15 is a fragmentary top plan view of a portion of the movable contact structure of Fig. 14, taken substantially along the line XV-XV of Fig. 14;

Fig. 16 is a view similar to that of Fig. 5, but is a sectional view taken through a modified type of arc-extinguisher;

Fig. 17 is a top plan view of one of the insulating strips employed in the modified arc-extinguisher of Fig. 16;

Fig. 18 is an end elevational view of the insulating strip shown in Fig. 17;

Figs. 19 and 20 are respectively side elevational, and top plan views of the conducting arc runner for either the arc-extinguisher of Fig. or for the modified arc-extinguisher of Fig. 16;

Figs. 21 and 22 are side elevational and top plan views, respectively, of the insulating top cover Plate of the housing structure for the arc-extinguisher; and,

Fig. 23 is a considerably enlarged end elevational view of the conducting arcing plate of Fig. 6, taken along the line XXIII-XXIII of Fig; 6, to more clearly illustrate the stamped mounting projections formed in the several conducting plates of the arc-extinguishing structure.

Referring to the drawings, and more particularly to Figs. 1 and 2 thereof, the reference numeral 1 generally designates a three-pole molded-case circuit interrupter, only the center pole being illustrated. The circuit interrupter 1 includes a base 2 and a cover 3, both preferably being formed of a suitable moldable material, as shown. As is apparent from the drawings, the base 2 and the cover 3 are molded with suitable recesses provided therein to accommodate the positioning therein of the several component parts of the interrupter -1 including an operating means 4.

The interrupter 1 also comprises a relatively stationary contact 5, supported on the end of a conducting strip 6, the latter being sharply turned upwardly, as at 7, away from the bottom, or lower external surface of the base 2, being terminated at its other end at a pressure-type line terminal connector 9.

Cooperating with the stationary contact 5 is a movable contact 11, carried at the outer free end of a singlebladed contact arm 1'2, the latter being pivotally mounted by a pivot pin 13 extending through pivot holes 13a to abifurcated switch arm 14, the latter being rotatable with an insulating tie bar 15 interconnecting the threepoles of the interrupter 1. The insulating tie bar 15 has pins 16 projecting outwardly from its ends, which pins 16 are supported by means not shown inthe side walls of the base 2. Thus, rotative movement of the insulating tie bar 15 will be effective to simultaneously cause opening or closing movement of the three switch arms 14 secured thereto.

. The, rotation of the insulating tie bar 15 is brought about by a toggle mechanism 17 including cooperable tog le links 18, 19 pivotally connected together by a knee pivot pin 21. The lower toggle link 19 actually comprises two toggle links, 19a and 1912 (Fig. 15), which have their lower ends pivotally connected by means of a pivot or limit pin 22 in the side legs 14a. and 14b of the. central bifurcated switch arm 14.

The upper end of the upper toggle link 18 is pivotally connected by means of a pivot pin 23 to a releasable cradle 24, which is pivotally mounted, by means of a pivot pin 25, between a pair of upstanding frame members 26. The frame members, 26 are rigidly secured, by means, not shown, to the base '2. A plurality of overcenter tension springs 27 are connected between the knee pivot pin 21 of the toggle mechanism 17 and a U shaped operating lever 28, having a handle 29 se cured. thereto, which projects through an opening 30 provided in the upper wall of the cover 3 above the middle. pole of the three-pole circuit interrupter 1. Thus, the operator, may grasp the handle 29 to effect opening and closingrotative movement of the U-shaped operating lever 28, the latter having a, pair of spaced, downwardly extending legs 31, the lower ends of which rotate in recesses 32 provided by the frame members 26.

From the foregoing description, it will be apparent to those skilled in the art that clockwise movement of the operating handle 29 will cause corresponding clockwise rotative movement of the. operating lever 28 to cause the overcenter springs 2'7 to exert their force to the right of the upper pivotal mounting 23 of the toggle mechanism 17. This will elfect straightening of the toggle links 18, 19 to a slightly overcenter position, as illustrated in Fig. 2, and will eifect contacting engagement between the movable contact 11 and the relatively stationary contact 5. On the other hand, counterclockwise movement of the handle 29 will bring the line of action of the overcenter springs 27 to the left of the pivotal mounting 23, as viewed in Fig. 1, and will eifect the collapse of the toggle mechanism 17 to the position indicated in Fig. 1, thereby effecting the separation between the relatively stationary and movable contacts 5, 11.

The circuit interrupter 1 also includes a tripping device, generally designated by the reference numeral 33, and described and claimed in United States patent application filed November 30, 1956, Serial No. 625,297, issued June 23, 1959 as US. Patent 2,892,054 to Eugene J. Walker and Howard E. Reichert, and assigned to the assignee of the instant application. Reference may be had to the aforesaid application for a detailed description and operation of the tripping device 33. This particular tripping device 33 is not an essential part of the present invention, and will, therefore, only briefly be described. Generally, the tripping device 33 includes an insulating trip bar 35, which extends across the three poles of the interrupter 1 and may be rotated by any one of three tripping screws 36, each of which is dispose at the outer end of a bimetallic strip 37 associated with each pole of the interrupter 1. A flexible conductor 33 electrically interconnects the outer end of each bimetallic element 37 with an L-shaped conducting bracket 39 having its outer end 40 connected to a second pressuretype load terminal connector 4-1.

To the lower end of the bimetallic strip 37 for each pole of the interrupter 1 is secured a conducting bracket 43 which is electrically connected by means of a flexible conductor 44 to the movable contact arm 12, in a manner more clearly shown in Fig. 14 of the drawings.

Thus, in the closed-circuit position of the interrupter 1, as shown in Figs. 2 and 14, the electrical circuit therethrough includes load terminal connector 41, connecting.

bracket 39, flexible connector 38, through bimetallic strip 37 to conducting bracket 43. The circuit then extends through the flexible connector 4'4, and through the contact arm 12 to the movable contact 11. The circuit then includes the relatively stationary contact 5 and conducting.

trip 6 to the other line terminal connector f the particular pole being considered, in this case the central pole of the interrupter 1.

As well known by those skilled in the art, upon the separation of the relatively stationary and movable contacts 5, 11, an arc will be established, and the provision of an arc-extinguisher to rapidly effect the extinction of this are is necessary. An important feature of the present invention is an improved unitary arc-extinguisher 45, which comprises a substantially U-shaped fiber wrapper or U-shaped extinguisher housing 46, the configuration of which is more readily apparent from an inspection of Figs. 11.-l3 of the drawings.

As illustrated in Figs. 11-13, the Ushaped wrapper 46 includes a pair of spaced, side wall portions 47 and an interconnecting bight portion 48, the latter having a depending tongue portion 49, which is bent forwardly, as illustratedin Fig. 11.

It. will be noted that each side wall 47 has an upper rear extension 50, which cooperates with a U-shaped, insulating, fiber cover plate or angularly-shaped insulating slotted cover plate portion 51 in a manner more clearly illustrated in Figs. 2 and 4 of the drawings. With particular reference being directed to Figs. 21 and 22. of the drawings, it will be noted that the slotted fiber cover plate 51 has a slot 51a therein. It is also provided with a plurality of recesses 52 along the outer side edges thereof, which recesses 52 cooperate with projecting mounting lugs, or bosses 53, which preferably are integrally formed with the side wall portions 47 of the U-shaped fiber wrapper or extinguisher housing 46. Thus, an interlocking mounting construction results.

As shown in Fig. 21, the fiber cover plate 51 has an upstanding wall portion or closure-plate portion 54, which cooperates with the extensions 50 of the side walls 47 of the wrapper 46 to result in a rearwardly disposed chimney extension 55, as indicated in Fig. 4 of the drawings. This chimney extension 55 is positioned immediately adjacent to a screened external gas exhaust vent 56, provided in one end wall of the cover 3 for the interrupter 1 and protrudes upwardly into a receptive or expansion space 3a provided by the cover 3. Fig. 3 more clearly shows the mesh screen 57, which is employed over the vent opening 56 to cool and deionize the exhaust gases, which are ejected out of the unitary arc-extinguisher 45 following an interrupting operation. 7

The U-shaped fiber wrapper 46, and the slotted fiber cover plate 5 1, collectively constitute a housing 58 for a plurality of spaced, conducting plates, which in this particular instance are preferably made from steel. Figs. 6-10, 19, 20 and 23 more clearly illustrate the several component parts of the plate structure. Fig. 6 illustrates, in plan, the longest steel plate, designated by the reference numeral 59. As illustrated in Fig. 6, it will be observed that the conducting steel plate 59 has formed therein a tapered single-ended slot or arc-receiving notch 60 terminating in an apex 62. The side legs .61 of the conducting plate 59 straddle the contact arm 12, as shown in Fig. 1. Each steel plate 59 also has hooked lug portions 63 provided along its outer edges together with an additional lug 64, as shown in Fig. 6. The U-shaped wrapper 46, as illustrated in Figs. 1 and 2, is provided with a plurality of suitably positioned slots or perforations 65, into which are projected, during the assembly operation, the side lugs 63, 64 of the several plates 59.

Adjacent the lower end of the arc-extinguisher 45, as more clearly shown in Fig. 4, are positioned additional steel plates 66, 67 and 68, which are shorter than the plates 59 of Fig. 6 because of the forward extension of the tongue 49 of the U-shaped wrapper 46. As a matter of fact, the plates 66, 67 and 68 may be formed from plates 59 of the type shown in Fig. 6 with the rear ends suitably cut oif. Again the plates 66-68 have the projecting lugs 63, 64, with the plates 67 only having the lugs 63, as shown in Fig. 8.

The top steel plate 68 of the arc-extinguisher 45 has a tab-like arc horn 69 secured thereto, as by spot welding. The are horn 69 facilitates the transfer thereto of the upper portion of the established are, the other end of which terminates at the movable contact 11. The top plate 68 is similar to the long plate 59, but has a length intermediate that of the plates 66 and 67, as will be apparent from a study of Fig. of the drawings. All of the plates 59, 66, 67 and 68 are punched, so as to provide oppositely extending mounting projections 70, more clearly shown in Fig. 23 of the drawings. These mounting projections 70 serve to locate, and to maintain in position, a plurality of insulating fiber plates 71 having holes 71a, the configuration of which is more clearly shown in Fig. 5 of the drawings. With reference to Fig. 5, it will be noted that the apex portion 72' of the slot 73 of the fiber plate 71 is enlarged, so as to be spaced away from the apices 62 of the adjacent conducting plates 59. The relieved throat 72 is indicated by the spacing D in Fig. 5. As illustrated in Fig. 4, preferably a fiber plate 71 is located between adjacent conducting plates,

and the fiber plates 71 provide a source for the evolu tionof gas during the travel of the established arc into the plate structure. More specifically, the magnetic plates 59, 66-68 attract the established are, drawn between the contacts 5 and 11, toward the apices 62 of the arc-receiving notches 60 of the several plates and cause the movement of the are into the plate structure, so as to be subdividedinto a plurality of serially related ares, designated by the reference numeral 74 in Fig. 4. The heat of the arcs 74 causes the evolution of considerable gas, which assists in bringing about the extinction of the arcs 74.

With'particular attention being directed to Fig. 4, it will be observed that the insulating U-shaped plates 71 diverge toward the right, so that venting spaces 10 exist between the bridging portions 75 of the plates 71 and the lower surfaces of the conducting plates 59, 66, 68 disposed thereabove. These venting spaces 10 permit the ready exhaust of gas toward the right, as viewed in Fig. 4, toward the vertical flow passages 88, hereinafter described.

Disposed at the lower end of the arc-extinguisher 45 is a steel arc runner 77, having a configuration more clearly illustrated in Figs. 19 and 20 of the drawings. As shown, the steel arc runner 77 has projecting mounting lugs 78, which pass through the slots 65 provided in the fiber wrapper 46 and is thus maintained in proper position.

During the opening operation, the contact arm 12 moves upwardly away from the stationary contact 5 from the position shown in Fig. 2 to the position shown in Fig. 1. The established arc is magnetically attracted into the slots 60 of the several magnetic plates toward the apices 62 thereof. Upon contacting the conducting plates 59, 66-68, the initially established arc is broken up into a plurality of serially related are portions '74, as shown in Fig. 4. These are portions 74 contact the bridging portions 75 of the fiber plates 71, thereby evolving a con- I siderable amount of unionized gas. Because 'of the notches 79 provided at the rear ends of the steel plates, the gas has a ready passage upwardly along the bight portion 48 of the U-shaped wrapper 46.

The advantages of employing notches at the rear corners of the magnetic plates 59, 6668 and the theory pertaining thereto are set forth and claimed in United States Patent 2,590,543, issued March 25, 1952, to John A. Kalaway, and assigned to the assignee of the instant application.

It will be observed that the relatively stationary contact 5 is disposed immediately adjacent to the bottom, or lower external surface 8 of the base 2, having only a short, completely insulated portion existing therebetween. By positioning the stationary contact 5 as near as possible, with adequate regard for electrical clearances, to the lower surface 8, and to the mounting surfaces 8' of the base 2, a maximum contact separation distance is possible in the fully open-circuit position of the interrupter 1, as illustrated in Fig. l of the drawings. It will be noted also that the upper contact surface of the stationary contact 5 is substantially below the lower surface 9' of the terminal 9, to the underside of which electrical connection is made by a bus connector 89 (Fig. l) or rear connecting stud, when the breaker is used in panelboards or switchboards.

By having the stationary contact position so low in the housing, more arc-extinguishing plates can be used above the contact and thus interrupt a higher voltage without increasing the size of the housing. The slant of the plates also contributes to this result since longer plates may be used without increasing the length of the breaker and without decreasing the size of the space 90 under the lower surface 9' of the terminal connector and under the slanting portion 7 of the conductor 6, which space 90 is necessarily provided for the bus connector 89 (Fig. 1) used in panelboards. It is, therefore, possible to provide a circuit interrupter capable of interrupting circuits up to 600 volts in a circuit interrupter housing of a size,

which previously had an upper interrupting voltage limit of only 250 volts DC It will be noted that the pivot point 16 for the mov able switch arm 14 is disposed on a level, which is sub stantially half way between the relatively stationary contact 5, below the arc-extinguisher 45, and the top plate 68 of the plate assembly, so that in the open-circuit position of the interrupter 1, as illustrated in Fig. 1, the movable contact 11 is disposed substantially as near to the stationary contact as any other conducting part of the movable contact arm 11.

The angle a in Fig. 2 indicates that the switch arm 12 is swung through as much an angle, or even a greater angle in the closed position relative to the horizontal line passing through the switch arm pivot 16, than the open circuit position throw of the switch arm, as indicated by the angle ,6.

Particular attention is directed to the fact that in combination with a greater contact separation distance, as provided by the present invention, with the contact 5 disposed as near the lower surface 8 of the base 2 as possible, the provision of the elongated slot 80 in the tail end of the contact arm 12, as more clearly shown in Fig. 14, together with the torsion biasing spring 81 encircling limit pin 22, permits the movable contact 11 to be thrust downwardly into the well or supporting recess 82, into which the stationary contact 5 is positioned.

As a result of the foregoing construction, the contact arm 12 is slanted downwardly into the well 82, as shown in Figs. 2 and 14, thereby providing a wide contact separation distance between the stationary and movable contacts 5, 11. Further, the slot 80 provided in the lefthand end of the contact arm 12' and the limit pin 22 constituting a lost-motion connection, together with the biasing spring 81, furnishes contact pressure in the closed circuit position, and moreover compensates for any contact wear occurring during the operational life of the interrupter 1.

Fig. 16 of the drawin s illustrates a modified unitary type of arc-extinguisher, generally designated by the reference numeral 84, which may be substituted for the unitary arc-extinguisher d5 of Fig. 4 in the circuit interrupter 1 of Fig. 1. With particular reference to Figs. 16-18, it will be observed that a pair of insulating strips or strip portions 85 are provided between adjacent conducting plates in the same manner that the insulating plates 71 of Fig. 5 were interspersed between the conducting plates, as illustrated in Fig. 4 of the drawings. Preferably, the insulating strips are formed of a suitable gas-evolving material, in this particular instance fiber, so that the heat of the initially established arc, and of the later formed serially related arcs 74, will cause the evolution of unionized gas from the fiber strips 85 to assist in arc extinction.

To facilitate the assembly of the modified type of arcextinguisher $4, the gas-evolving insulating strips 85 are provided with holes 86, which cooperate with the punched portions 70 of the conducting plates to maintain the strips 85 in their proper position, as shown in Fig. 16 of the drawings.

With particular attention being directed to Fig. 16, it will be noted that extensions 37 of the insulating strips 85 extend along the side legs 61. of the conducting plates 59, 6668, so that the initially established are between the contacts 5 and 11 will be drawn in immediate proximity thereto, thereby assisting initially in the formation of additional unionized gas.

In both arc-extinguishers 45, 84 the conducting plates 59, 66-68 diverge slightly toward the rear of the arcextinguishers to facilitate the rearward exhaust of gas through the extinguishers 45, 84, and upwardly through the two continuous vertical passages 88, provided by the several notches 79. As mentioned previously, the vertical continuous passages 88 communicate with the rearwardly disposed chimney extension 55 formed by the extensions 50 of the side wall portions 47 of the wrapper 46, leading to the screened external vent opening 56 provided in the cover 3.

From the foregoing description of the present invention, it will be apparent that there is provided an improved arc-extinguisher having alternate fiber and magnetic arcing plates. In addition, there is employed a magnetic are runner 77, upper arc horn 69 all enclosed in a fiber cover plate 51 and a fiber wrapper 46. The extended top 50 of the fiber wrapper 46 directs the arc gases through a screened vent 56 in the breaker cover 3. Intermediate fiber arcing plates 71, as shown in Fig. 5, with a relieved throat 72 assist in arc interruption, and the punched projections 70, provided in the steel arcing plates, assist in the assembly of the arc-extinguisher and in the retention of the fiber plates 71 or 85.

As observed in Fig. 4, the arc runner 77 is positioned and retained in the fiber wrapper 46, as are the several magnetic plates 59, 65-68. The chimney extension 55 cooperates with the notches 79 provided in the plates, forming the two cooperating continuous vertical flow passages 88, to give the arc-extinguishers 45, 84 a chimney effect to direct the arc gases toward the screened vents 56 provided in the breaker cover 3.

The spacings between the arcing plates in the assembly are greater at the throat end of the plate than at the open ends so that the gases may flow beween the plates, up the back of the arc-extinguishers and through the openings 88 made by the notched corners 79 of the steel plates. In addition, by locating the pivot point 16 of the movable contact assembly on a line approximately half way between the stationary contact 5 and the top arcing plate 68 an extremely wide con-tact separation distance is possible, with the movable contact 11 being the point of opposite potential nearest to the stationary contact 5 in the open-circuit position of the interrupter 1, as shown in Fig. 1.

The net result of all of the foregoing advantages is to considerably raise the interrupting level of the circuit interrupter, so that even though the base and cover are of about the same over-all dimensions that were formerly used for lower-rating interrupters, a considerable increase of interrupting ability has been attained, as attested by the fact that the interrupter is suitable for circuits of 600 volts.

Although there have been shown and described specific structures, it is to be understood that the same were merely for the purpose of illustration, and that changes and modifications may readily be made therein by those skilled in the art Without departing from the spirit and scope of the invention.

We claim as our invention:

1. An air-break circuit interrupter including a twopart molded enclosing casing, the two-part molded enclosing casing including an enclosing molded base of molded insulating material and a cooperating molded top cover also of molded insulating material, the molded'base having a bottom wall, end walls and an open top, the cooperating molded top cover having an upper wall, end walls and having the lower side thereof open to register with the open top of the molded base, a handle-opening provided through said upper wall of the top cover, a lineterminal connector secured to one end wall of the molded base and a load-terminal connector secured to the opposite end wall of the molded base, the molded insulating base having a supporting recess molded integrally therewith adjacent the line-terminal connector, the molded top cover having portions integrally molded therewith defining a receptive space generally in registration with said supporting recess of the base, a relatively stationary contact positioned at the bottom of the supporting recess in the molded base, a pivotally-mounted contact arm carrying a movable contact at the outer free end thereof, the movable contact being cooperable with the relatively stationary contact to draw an arc therebetween generally normally to the bottom wall of the molded base and lengthening toward the open upper end of the base adjacent said line-terminal connector, operating means including a manually-operable handle extending through said handle opening in the cover for actuating said pivotally-mounted contact arm, a unitary arc-extinguishing structure for extinguishing said are and adapted to be bodily positioned within said supporting recess in the base and with the upper end of the are-extinguishing structure protruding upwardly within said receptive space within the molded top cover, said unitary arc-extinguishing structure including a stack of spaced metallic conducting plates, at least some of the metallic conducting plates having pairs of legs defining single-ended slots having apices extending inwardly from the front ends of the plates and generally along the central axes thereof, the single-ended slots being substantially aligned to form an arcing path, an insulating generally U-shaped extinguisher housing substantially enclosing the rear ends of the metallic plates and maintaining them in spaced relationship, said pivotally-mounted contact arm moving between the several pairs of legs of the metallic conducting plates, the rear ends of the conducting plates being disposed more closely to said line-terminal connector than the front ends thereof, said conducting plates being slanted at an angle upwardly away from the bottom wall of the molded base and toward the open top thereof, only the rear portions of the two side Walls of the generally U-shaped extinguisher housing adjacent said apices extending upwardly beyond the rear bight portion of the generally U-shaped housing, a front-facing upwardly-extending closure-plate portion in the vicinity of said apices connecting the frontfacing edges of said upwardly-extending rear portions of the two side walls of the housing constituting thereby a rear-vented, upwardly-extending chimney portion, said upwardly-extending chimney portion extending upwardly beyond the rear end of the top conducting plate of said stack of plates and into said receptive space within the molded top cover, means defining a gas-exhaust vent adjacent one end of said molded top cover communicating 'with the receptive space of the cover, the venting space within the chimney portion immediately beyond the rear bight portion of the generally U-shaped extinguisher housing generally registering with said gas-exhaust vent of the top molded cover, and the arc-extinguishing structure functioning to split up the initially established are drawn along said arcing path into a plurality of serially related are portions extending between the spaced conducting plates and to vent the heated arc gases through said chimney portion and out of the circuit interrupter casing through said gas-exhaust vent in the molded top cover.

2. An air-break circuit interrupter including a two-part molded enclosing easing, the two-part molded enclosing casing including an enclosing molded base of molded insulating material and a cooperating molded top cover also of molded insulating material, the molded base having a bottom wall, end walls and an open top, the cooperating molded top cover having an upper Wall, end walls and having the lower side thereof open to register with the open top of the molded base, a handle-opening provided through said upper wall of the top cover, a lineterminal connector secured to one end wall of the molded base and a load-terminal connector secured to the opposite end wall of the molded base, the molded insulating base having a supporting recess molded integrally therewith adjacent the line-terminal connector, the molded top cover having portions integrally molded therewith defining a receptive space generally in registration with said supporting recess of the base, a relatively stationary contact positioned at the bottom of the supporting recess in the molded base, a pivot-ally-moun-ted contact arm carrying a movable contact at the outer free end thereof, the movable contact being eooperable with the relatively stationary contact to draw an arc therebetween generally normally to the bottom wall of the molded base and lengthening toward the open upper end of the base adjacent said line-terminal connector, operation means including a manually-operable handle extending through said handle opening in the cover for actuating said pivotally-mounted contact arm, a unitary arc-extinguishing structure for extinguishing said are and adapted to be bodily positioned within said supporting recess in the base and with the upper end of the arc-extinguishing structure protruding upwardly within said receptive space within the molded top cover, said unitary arc-extinguishing structure including a stack of spaced metallic conducting plates, at least some of the metallic conducting plates having pairs of legs defining single-ended slots having apices extending inwardly from the front ends of the plates and generally along the central axes thereof, the single-ended slots being substantially aligned to form an arcing path, an insulating generally U-shaped extinguisher housing substantially enclosing the rear ends of the metallic plates and maintaining them in spaced relationship, said pivotally-mounted contact arm moving between the several pairs of legs of the metallic conducting plates, the rear ends of the conducting plates being disposed more closely to said line-terminal connector than the front ends thereof, said conducting plates being slanted at an angle upwardly away from the bottom wall of the molded base and toward the open top thereof, only the rear portions of the two side walls of the generally U-shaped extinguisher housing adjacent said apices extending upwardly beyond the rear bight portion of the generally U-shaped housing, a front-facing upwardly-extending closure-plate portion in the vicinity of said apices connecting the front-facing edges of said upwardly-extending rear portions of the two side walls of the housing constituting thereby a rearvented, upwardly-extending chimney portion, said upwardly-cxtending chimney portion extending upwardly beyond the rear end of the top conducting plate of said stack of plates and into said receptive space within the molded top cover, means defining a gas-exhaust vent adjacent one end of said molded top cover communicating with the receptive space of the cover, the venting space within the chimney portion immediately beyond the rear bight portion of the generally U-shaped extinguisher housing generally registering with said gas-exhaust vent of the top molded cover, the arc-extinguishing structure functioning to split up the initially established are drawn along said arcing path into a plurality of serially related arc' portions extending between the spaced conducting plates and to vent the heated are gases through said chimney portion and out of the circuit interrupter easing through said gas-exhaust vent in the molded top cover, and each of a plurality of said stack of spaced metallic conducting plates having a pair of notches provided therein at the rear corners thereof, the several notches aligning and cooperating with the bight portion of the generally U-shaped housing to define two continuous venting passages at the rear corners of the plates to minimize back pressure of the formed are gases and to permit eommunication with the upwardly-extending chimney portion.

I 3. An air-break circuit interrupter including a two-part molded enclosing casing, the two-part molded enclosing casing including an enclosing molded base of molded insulating material and a cooperating molded top cover also of molded insulating material, the molded base having a bottom wall, end walls and an open top, the cooperating molded top cover having an upper wall, end walls and having the lower side thereof open to register with the open top of the molded base, a handle-opening provided through said upper wall of the top cover, a line-terminal connector secured to one end wall of the molded base and a load-terminal connector secured to the opposite end wall of the molded base, the molded insulating base having a supporting recess molded integrally therewith adjacent the line-terminal connector, the molded top cover having portions integrally molded therewith defining a receptive space generally in registration with said supporting recess of the base, a relatively stationary contact positioned at the bottom of the supporting recess in the molded base, a pivotally-mounted contact arm carrying a movable contact at the outer free end thereof, the movable contact being cooperable with the relatively stationary contact to draw an arc therebetween generally normally to the bottom wall of the molded base and lengthening toward the open upper end of the base adjacent said line-terminal connector, operating means including a manually-operable handle extending through said handle opening in the cover for actuating said pivotally-mounted contact arm, a unitary arc-extinguishing structure for extinguishing said are and adapted to be bodily positioned within said supporting recess in base and with the upper end of the arc-extinguishing structure protruding upwardly within said receptive space within the molded top cover, said unitary arc-extinguishing structure including a stack of spaced metallic conducting plates, at least some of the metallic conducting plates having pairs of legs defining single-ended slots having apices extending inwardly from the front ends of the plates and generally along the central axes thereof, the single-ended slots being substantially aligned to form an arcing path, an insulating generally U-shaped extinguisher housing substantially enclosing the rear ends of the metallic plates and maintaining them in spaced relationship, said pivotally-mounted contact arm moving between the several pairs of legs of the metallic conducting plates, the rear ends of the conducting plates being disposed more closely to said line-terminal connector than the front ends thereof, said conducting plates being slanted at an angle upwardly away from the bottom wall of the molded base and toward the open top thereof, only the rear portions of the two side Walls of the generally U-shaped extinguisher housing adjacent said apices extending upwardly beyond the rear bight portion of the generally U-shaped housing, a front-facing upwardly-mo tending closure-plate portion in the vicinity of said apices connecting the front-facing edges of said upwardly-extending rear portions of the two side walls of the housing constituting thereby a rear-vented, upwardly-extending chimney portion, said upwardly-extending chimney portion extending upwardly beyond the rear end of the top conducting plate of said stack of plates and into said receptive space within the molded top cover, means defining a gas-exhaust vent adjacent one end of said molded top cover communicating with the receptive space of the cover, the venting space within the chimney portion immediately beyond the rear bight portion of the generally U-shaped extinguisher housing generally registering with said gas-exhaust vent of the top molded cover, the arcextinguishing structure functioning to split up the initially established are drawn along said arcing path into a plurality of serially related arc portions extending between the spaced conducting plates and to vent the heated arc gases through said chimney portion and out of the circuit interrupter casing through said gas-exhaust vent in the molded top cover, said insulating generally U-shaped extinguisher housing being formed as a U-shaped wrapper from a single piece of bendable, relatively-thin, insulating sheet material having perforations therethrough, and said conducting plates having lug extensions at the outer side edges thereof protruding through said perforations of the U-shaped wrapper to firmly secure the metallic plates and the wrapper together.

4. An air-break circuit interrupter including a two-part molded enclosing casing, the two-part molded enclosing casing including an enclosing molded base of molded insulating material and a cooperating molded top cover with the open top of the molded base, a handle-opening provided through said upper wall of the top cover, a line-terminal connector secured to one end wall of the molded base and a load-terminal connector secured to the opposite end wall of the molded base, the molded insulating base having a supporting recess molded integrally therewith adjacent the line-terminal connector, the molded top cover having portions integrally molded therewith defining a receptive space generally in registration with said supporting recess of the base, a relatively stationary contact positioned at'the bottom of the supporting recess in the molded base, a pivotallyr-mounted contact arm carrying a movable contact at the outer free end thereof, the movable contact being cooperable with the relatively stationary contact to draw an are therebetween generally normally to the bottom wall of the molded base and lengthening toward the open upper end of the base adjacent said line-terminal connector, operating means including a manually-operable handle extending through said handle opening in the cover for actuating said pivotally-mounted contact arm, a unitary arc-extinguishing structure for extinguishing said are and adapted to be bodily positioned within said supporting recess in the base and with the upper end of the arc-extinguishing structure protruding upwardly within said receptive space within the molded top cover, said unitary arcextinguishing structure including a stack of spaced metallic conducting plates, at least some of the metallic conducting plates having pairs of legs defining single-ended slots having apices extending inwardly from the front ends of the plates and generally along the central axes thereof, the single-ended slots being substantially aligned to form an arcing path, an insulating generally U-shaped extinguisher housing substantially enclosing the rear ends of the metallic plates and maintaining them in spaced relationship, said pivotally-mounted contact arm moving between the several pairs of legs of the metallic conducting plates, the rear ends of the conducting plates being disposed more closely to said line-terminal connector than the front ends thereof, said conducting plates being slanted at an angle upwardly away from the bottom wall of the molded base and toward the open top thereof, only the rear portions of the two side walls of the generally U-shaped extinguisher housing adjacent said apices extending upwardly beyond the rear bight portion of the generally U-shaped housing, a front-facing upwardlyextending closure-plate portion in the vicinity of said apices connecting the front-facing edges of said upwardlyextending rear portions of the two side walls of the housing constituting thereby a rear-vented, upwardly-extending chimney portion, said upwardly-extending chimney portion extending upwardly beyond the rear end of the top conducting plate of said stack of plates and into said receptive space within the molded top cover, means defining a gas-exhaust vent adjacent one end of said molded top cover communicating with the receptive space of the cover, the venting space within the chimney portion immediately beyond the rear bight portion of the generally U-shaped extinguisher housing generally registering with said gas-exhaust vent of the top molded cover, the arc-extinguishing structure functioning to split up the initially established are drawn along said arcing path into a plurality of serially related arc portions extending between the spaced conducting plates and to vent the heated arc gases through said chimney portion and out of the circuit interrupter casing through said gas-exhaust vent in the molded top cover, and a plurality of spaced pairs of strip portions of gas-evolving insulating material being interspersed between said spaced metallic conducing plates to assist in arc extinction by the evolution of de-ionizing gas.

5. The combination in a molded-case air-break circuit.

13 bottom wall, end walls and an open top, the registering molded top cover having an upper wall, end walls and having the lower side thereof open to register with the open top of the molded base, a line-terminal connector secured to one end wall of the molded base and a loadterminal connector secured to the opposite end wall of the molded base, the molded base having a supporting recess molded integrally therewith adjacent the lineterminal connector, the molded top cover having portions integrally molded therewith defining an expansion space generally in registration with said supporting recess of the base, a relatively stationary contact positioned at the bottom of the supporting recess in the molded base,

a pivotally-mounted contact arm carrying a movable contact at the outer free end thereof, the movable contact being separable from the relatively stationary contact to draw an arc therebetween generally perpendicularly to the bottom wall of the molded base with the arc lengthening toward the open upper end of the base adjacent said line-terminal connector, a unitary arc-extinguisher for extinguishing said are and adapted to be bodily positioned within said supporting recess in the base and with the upper end of the unitary arc-extinguisher extending upwardly into said expansion space within the molded top cover, said unitary arc-extinguisher including a stack of spaced metallic conducting plates, at least some of the metallic conducting plates having pairs of legs defining arc-receiving notches extending inwardly from the front ends of the plates and generally along the central axes thereof, corresponding legs on corresponding sides of the plates being aligned with each other and with the arc-receiving notches also aligning to form an arcing path, an insulating generally U-shaped extinguisher housing substantially enclosing the rear ends of the metallic plates and supporting them in spaced relationship, the rear ends of the conducting plates being disposed more closely to said line-terminal connector than the front ends thereof, said conducting plates being slanted at an angle upwardly away from the bottom wall of the molded base and toward the open top thereof, only the rear upper corner portions of the two side walls of the generally U-shaped extinguisher housing extending upwardly beyond the rear yoke portion of the generally U-shaped extinguisher housing, an. angularly-shaped insulating slotted cover-plate portion bridging portions of the upper sides of the two side walls and also the front-facing edges of said upwardly extending rear corner portions, an integrally formed slotted-plate portion of said cover-plate portion being positioned generally parallel to the planes of said stack of conducting plates and bridging the upper edges of the two side walls adjacent the front of the arc extinguisher, another integrally formed upwardly-extending front-facing plate portion of said cover-plate portion bridging the front-facing edges of said upwardly-extending rear corner portions of the two side walls constituting thereby a rear-vented upwardly-extending chimney portion, said upwardly-extending chimney portion extending upwardly beyond the rear end of the top conducting plate of said stack of plates and into said expansion space within the molded top cover, said pivotally-mounted contact arm moving between the several pairs of legs of the metallic conducting plates and also through the slot portion of said angularly-shaped slotted cover-plate portion, means forming an exhaust vent adjacent one end of said molded top cover communicating with the expansion space within said molded top cover, the venting space within said chimney portion immediately beyond the rear yoke portion of the generally U-shaped extinguisher housing generally registering with said exhaust vent of the top molded cover, the arc extinguisher operating to split up the initially established are drawn along said arcing path into a plurality of serially related arc portions extending between the spaced conducting plates and to vent the heated arc gases through said upwardlyextending chimney portion and out of the molded circuitinterrupter casing through the exhaust vent in the molded top cover, the generally U-shaped extinguisher housing being formed as a U-shaped wrapper from a single piece of bendable, relatively thin, insulating sheet material having perforations therethrough, the said conducting plates having lug extensions at the outer side edges thereof protruding through said perforations of the U- shaped Wrapper to firmly secure the metallic plates and the wrapper together, and said angularly-shaped insulating slotted cover-plate portion being formed from a separate piece of bendable, re1ativelythin insulating sheet material and secured to the upper side walls of the U- shaped wrapper.

6. The combination in a molded-case air-break circuit interrupter of an enclosing molded base of molded insulating material and a registering molded top cover also of molded insulating material, the molded base having a bottom wall, end walls and an open top, the registering molded top cover having an upper wall, end walls and having the lower side thereof open to register with the open top of the molded base, a line-terminal connector secured to one end wall of the molded base and a loadterminal connector secured to the opposite end Wall of the molded base, the molded base having a supporting recess molded integrally therewith adjacent the lineterminal connector, the molded top cover having portions integrally molded therewith defining an expansion space generally in registration with said supporting recess of the base, a relatively stationary contact positioned at the bottom of the supporting recess in the molded base, a pivotally-mounted contact arm carrying a movable contact at the outer free end thereof, the movable contact being separable from the relatively stationary contact to draw an arc therebetween generally perpendicular" ly to the bottom wall of the molded base with the arc lengthening toward the open upper end of the base adjacent said line-terminal connector, a unitary arc-extinguisher for extinguishing said are and adapted to be bodily positioned within said supporting recess in the base and with the upper end of the unitary arc-extinguisher extending upwardly into said expansion space within the molded top cover, said unitary arc-extinguisher including a stack of spaced metallic conducting plates, at least some of the metallic conducting plates having pairs of legs defining arc-receiving notches extending inwardly from the front ends of the plates and generally along the central axes thereof, corresponding legs on corresponding sides of the plates being aligned with each other and with the arc-receiving notches also aligning to form an arcing path, an insulating generally U-shaped extinguisher housing substantially enclosing the rear ends of the metallic plates and supporting them in spaced relationship, the rear ends of the conducting plates being disposed more closely to said line-terminal connector than the front ends thereof, said conducting plates being slanted at an angle upwardly away from the bottom wall of the molded base and toward the open top thereof, only the rear upper corner portions of the two side walls of the generally U-shaped extinguisher housing extending upwardly beyond the rear yoke portion of the generally U-shaped extinguisher housing, an angularly-shaped insulating slotted cover-plate portion bridging portions of the upper sides of the two side walls and also the front-facing edges of said upwardly extending rear corner portions, an integrally formed slotted-plate portion of said coverplate portion being positioned generally parallel to the planes of said stack of conducting plates and bridging the upper edges of the two side walls adjacent the front of the arc extinguisher, another integrally formed upwardly-extending front-facing plate portion of said coverplate portion bridging the front-facing edges of said upwardly-extending rear corner portions of the two side walls constituting thereby a rear-vented upwardly-extending chimney portion, said upwardly-extending chimney portion extending upwardly beyond the rear end of the top conducting plate of said stack of plates and into said expansion space within the molded top cover, said pivotally-mounted contact arm moving between the several pairs of legs of the metallic conducting plates and also through the slot portion of said angularly-shaped slotted coverplate portion, means forming an exhaust vent adjacent one end of said molded top cover communicating with the expansion space within said molded top cover, the venting space within said chimney portion immediately beyond the rear yoke portion of the generally tJ-shaped extinguisher housing generally re istering with said exhaust vent of the top molded cover, the arc extinguisher operating to split up the initially established arc drawn along said arcing path into a plurality of serially related are portions extending between the spaced conducting plates and to vent the heated arc gases through said upwardly-extending chimney portion and out of the molded circuit-interrupter casing through the exhaust vent in the molded top cover, and a tab-like arcing horn being conductiveiy secured to the top conducting metallic plate of the stack of plates and extending upwardly through the slot of said slotted cover-plate portion.

7. A circuit interrupter including a bifurcated switch arm having a pair of leg portions, means pivotally mounting said bifurcated switch arm adjacent one end thereof, a single-bladed contact arm mounted between said leg portions of the switch arm, a movable contact portion disposed at one outer free end of the singlebladed contact arm, a pivot hole provided intermediate the ends of the contact arm, pivot-mounting holes provided at the free ends of the leg portions of the switch arm, a pivot pin passing with small clearance through the pivot hole of the contact arm and through the pivot mounting holes at the free ends of the leg portions, a lost-motion connection between the contact and switch arms including an elongated slot provided at the other tail end of the contact arm disposed between the leg portions, a limit pin fixedly mounted intermediate the ends of the leg portions of the switch arm and passing through said elongated slot of the contact arm, a torsion spring encircling said limit pin and biasing the contact arm in its closing direction relative to the switch arm, a relatively stationary contact cooperable with the movable contact portion to establish an are, said contact arm being biased about said pivot pin between the leg portions of the switch arm with a lost motion therebetween as determined by the distance the limit pin moves within the elongated slot of the contact arm, the torsion spring providing contact pressure in the closed-circuit position of the interrupter, a toggle mechanism being provided to effect opening and closing pivotal motion of the switch 16 arm, and said toggle mechanism including one or more toggle links pivotally connected to said limit pin.

8. A circuit interrupter including a bifurcated switch arm having a pair of leg portions, means pivotally mounting said bifurcated switch arm adjacent one end thereof, a single-bladed contact arm mounted between said leg portions of the switch arm, a movable contact portion disposed at one outer free end of the single-bladed contact arm, a pivot hole provided intermediate the ends of the contact arm, pivot-mounting holes provided at the free ends of the leg portions of the switch arm, a pivot pin passing with small clearance through the pivot hole of the contact arm and through the pivot mounting holes at the free ends of the leg portions, alost-motion connection between the contact and switch arms including an elongated slot provided at the other tail end of the contact arm disposed between the leg portions, a limit pin fixedly mounted intermediate the ends of the leg portions of the switch arm and passing through said elongated slot of the contact arm, a torsion spring encircling said limit pin and biasing the contact arm in its closing direction relative to the switch arm, a relatively stationary contact cooperable with the movable contact portion to establish an arc, said contact arm being biased about said pivot pin between the leg portions of the switch arm with a lost motion therebetween as determined by the distance the limit pin moves within the elongated slot of the contact arm, and the torsion spring providing contact pressure in the closed-circuit position of the interrupter.

References Cited in the file of this patent UNITED STATES PATENTS 2,047,739 Lingal July 14, 1936 2,073,965 Jackson Mar. 16, 1937 2,133,158 Ver Planck et a1 Oct. 11, 1938 2,140,360 Jennings "a Dec. 13, 1938 2,147,419 Baker Feb. 14, 1939 2,215,797 Sauer Sept. 24, 1940 2,243,038 Ludwig May 20, 1941 2,244,061 Graves June 3, 1941 2,318,298 Dorfman et al. May 4, 1943 2,363,606 Maseng Nov. 28, 1944 2,590,543 Kalaway Mar. 25, 1952 2,623,141 Wilckens Dec. 23, 1952 2,632,826 Titus Mar. 24, 1953 2,719,203 Gelzheiser et al. Sept. 27, 1955 FOREIGN PATENTS 715,121 Great Britain Sept. 8, 1954 732,196 Great Britain June 22, 1955 

